//正例
//{ before: false, after: false }
const arr = [,];
const arr = [ ,];
const arr = [1,];
const arr = [,2];
const arr = [ ,2];
const arr = [1,2];
const arr = [,,];
const arr = [ ,,];
const arr = [1,,];
const arr = [,2,];
const arr = [ ,2,];
const arr = [,,3];
const arr = [1,2,];
const arr = [,2,3];
const arr = [1,,3];
const arr = [1,2,3];
const a = (1 + 2,2)
const arr = [ , , ];